Field of the Invention
The invention relates to a handheld electronic apparatus, a sound producing system thereof and a control method of sound producing thereof, and particularly relates to a handheld electronic apparatus capable of compensating harmonic distortion of a speaker, a sound producing system thereof and a control method of sound producing thereof.
Description of Related Art
In recent years, in order to provide high quality multimedia functions, electronic apparatus is generally configured with a high quality sound producing system. In the conventional technical field, a speaker in the sound producing system is generally limited by factors of the maximum excursion, temperature raise, non-linear characteristics of a transducer, and non-linear factors caused by an amplifier corresponding to the speaker. Therefore, manufacturers determine the method for driving the speaker, by which the speaker is driven by a rated power in a long-term period, and is driven by the highest power in a short-term period. The aforementioned limitation conditions of driving power intend to limit the maximum excursion and the temperature raise of the speaker to be within a safety range. In order to reproduce signals with a wide dynamic range without distortion, loudness of the speaker is decreased, which especially occurs on a handheld device operated under the power limitation conditions. Therefore, in recent decades, a dynamic range compression technique is generally adopted to control the driving operation of the speaker, so as to make a balance between the distortion and the loudness.
Moreover, the conventional technique further provides a method for first compensating an input audio signal and then amplifying the compensated audio signal, though the compensation operation performed to the original input audio signal is rather complicated, and it has high difficulty in implementation to complete the accurate compensation operation.